S4708 The Ulcer That Wasn't: Gastric Amyloidosis Masquerading as Refractory Upper Gastrointestinal Bleeding

Introduction: Gastric involvement in systemic amyloidosis is a rare and often underdiagnosed cause of upper gastrointestinal (GI) bleeding. Clinical manifestations are nonspecific and may include early satiety, weight loss, or recurrent bleeding, often mimicking peptic ulcer disease or malignancy. Endoscopic findings are frequently subtle, and biopsies are sometimes deferred during active bleeding. We present a case of gastric amyloidosis identified after nearly a year of recurrent GI bleeding and repeated non-diagnostic endoscopies. Case Description/Methods: An 84-year-old man with low-grade myelodysplastic syndrome, stage V chronic kidney disease, coronary artery disease, and type 2 diabetes presented to our hospital with progressive weakness, orthostatic dizziness, and melena. He was on low-dose aspirin, denied nonsteroidal anti-inflammatory drug use, and was not taking anticoagulants. Over the past year, he had multiple hospitalizations for recurrent upper GI bleeding. Prior esophagogastroduodenoscopies (EGDs) revealed large ulcers in the gastric fundus and antrum with adherent clots, treated with over-the-scope clips and epinephrine injection. Biopsies were deferred due to active bleeding and poor visualization. On this admission, he was hemodynamically stable with melena on exam and a hemoglobin of 9.7 g/dL. Intravenous pantoprazole was initiated. Given his recurrent bleeding with no clear etiology on prior evaluations, serum, and urine protein electrophoresis with immunofixation were performed to assess for possible plasma cell dyscrasia. Free light chain assay showed elevated kappa and lambda levels, with a kappa-to-lambda ratio of 2.43—within the renal-adjusted range. Repeat esophagogastroduodenoscopy revealed a 1 cm ulcerated mass in the gastric fundus with granulation tissue and a previously placed clip. No active bleeding was noted. Biopsies showed chronic gastritis and ulceration. Congo red staining confirmed submucosal amyloid deposits with apple-green birefringence, diagnostic of gastric amyloidosis. The patient was discharged on oral pantoprazole twice daily with outpatient hematology-oncology follow-up for suspected AL amyloidosis. Discussion: This case highlights the diagnostic challenge of gastric amyloidosis, particularly when biopsies are delayed due to acute bleeding. In patients with chronic kidney disease, free light chain ratios may be misleading. Deep biopsies with Congo red staining remain essential for diagnosis. Early recognition can prevent delays in initiating systemic therapy for AL amyloidosis.